U.S. Pat. Nos. 4,415,729 and 4,524,200 disclose a "water quench" method of separating and recovering particulate poly(arylene sulfide) from reaction mixtures wherein polyhalo-substituted aromatic compounds have been converted in the presence of a polar organic solvent. These patents also disclose that a poly(arylene sulfide) oligomer fraction is present in the reaction mixtures and can be separated from said particulate poly(arylene sulfide). The reference in the above patents to the oligomer fraction as "slime" and its indicated fine particle size ("fines") reveals the difficulties previously encountered in handling these poly(arylene sulfide) oligomers. In fact, the above patents disclose the recovery of said oligomers on filters coated with a filter aid and the subsequent discarding of the mixture of filter aid and poly(arylene sulfide) oligomers scraped periodically from the filters. It will be recognized that it would be desireable to reduce the relative amount of the oligomer fraction in the poly(arylene sulfide) reaction product if for no other reason than to reduce the magnitude of the separation operation. It will also be apparent that discarding the poly(arylene sulfide) oligomers represents an economic penalty because expensive reactants have been consumed in the formation of these polymeric products. Furthermore, it is known that poly(phenylene sulfide) oligomers, if recovered, can be cured to useful products (U.S. Pat. No. 4,046,749).
It is therefore an object of this invention to provide a method for reducing the amount of poly(arylene sulfide) oligomers generally obtained in the "water quench" method of separation and recovery of poly(arylene sulfide).
It is another object of this invention to provide a method for separating the reaction mixture of the reaction of polyhalo-substituted aromatic compounds and polar organic solvent which has produced poly(arylene sulfide) into poly(arylene sulfide) oligomers and other components that can be separated for recovery or disposal. It is another object of this invention to provide a method for improving the filterability of poly(arylene sulfide) oligomers obtained in the "water quench" method of separation and recovery of poly(arylene sulfide). It is yet another object of this invention to provide a method for recovery of poly(arylene sulfide) oligomers in a form which is easily treatable by further processing to give useful products.